Scope Of Retrofitting in Nepal

Households Details in Nepal 

There are around 6 million houses in Nepal and Among them 2.5 a million houses are in earthquake-affected 32 districts. Among them, 1.1 million houses are in earthquake-affected 32 districts and altogether around 3.5 million houses nationwide, which need a seismic retrofitting in any form.  Among all beneficiaries of NRA around 70,000 houses are listed in retrofitting categories, they are retrofitting beneficiaries.

And around 300 schools were retrofitted before the Gorkha earthquake and their performance was well during the earthquake in 2015.

Retrofitting

It is a process of strengthening the existing structures to reduce vulnerability to damage during a future earthquake. There are different types of retrofitting techniques for different types of buildings. Techniques vary with the existing performance of building and structure type.

Popular retrofitting techniques are:

• Splints and bandage
• Wall Jacketing
• Strengthening of footing
•  Beam jacketing
•  Column jacketing
• Steel bracing
• Use of carbon fiber etc.

 There are manuals for each type of technique, which are available in the market and indifferent government sites and Non-governmental sites. You can check out there for more knowledge and information.

Scope of retrofitting

Since there are around 3.5 million private houses and many schools, hospitals and other buildings are available for retrofitting, there are many opportunities and scopes. Many schools, hospital buildings, etc. are being retrofitted. And challenges are in private house retrofitting in rural areas of countries.

Strategies for private house retrofitting in rural areas

 Retrofitting Champaign  

People should be aware of retrofitting and they should know why to do retrofitting and the benefits of retrofitting.

When they will know why is it better to retrofit existing house rather than build the same type of new house, they will mentally ready for it.

Promotion of Economic Technology

For private house retrofitting, the cost should be minimum as far as possible. Among many techniques of retrofitting, first, need to choose economic retrofitting techniques and should promote them in rural areas.

Capacity building of local Artisan

Since retrofitting is the new technology in rural areas, the first thing we need is capable masons through training and all ways possible.

In Addition to scope,

Retrofitting of the house with wield wire mesh (WWM) and GI wires

Materials Needed:

Local materials are sufficient except for listed Non-local materials.

Non-Local Materials:

• WWM
•   GI wires

The sequence of Installation of Retrofitting Measures on Walls  

1. All horizontal belts-lintel, floor, roof, and sill are installed on both faces of a wall simultaneously and are fixed to the wall with cross links tightly inserted through holes of diameters no greater than 15mm without any grout

2. All ‘L’ and ‘T’ corner splints are fixed to one face of the wall with “L” shaped shear connectors 9” deep in the hole of diameter not exceeding 100mm with concrete in it and 6” leg on wall face anchoring the WWM splint with 1mm GI binding wires.

 Typically, in 6 to 7' high walls encountered in traditional houses there should be 3 shear connectors on each wall. Shear connectors are installed at least one day ahead of the installation of WWM splints.

3. Install all opening encasements on both faces of the wall and anchor them to walls with cross-links. Skip encasement if the opening has a double frame

4. All vertical wires are anchored with cross-links on both wall's faces at required vertical spacing simultaneously. While going over the belt alignment they are anchored to the belt WWM with 1mm GI binding wires which are already anchored to walls. There is no need for additional cross-links for vertical wires within belt alignment. Vertical wires are not required where WWM Splints for opening encasement and wall junctions are installed.

5. All horizontal wires are installed between the belts and any other open spaces, but not on the belts. These wires are securely connected to already fixed vertical wires with 1mm GI binding wires in close vicinity of the cross-links that anchor the vertical wires. No cross-link anchors are needed exclusively for the horizontal wires.

6. Cement plaster must be applied on WWM belts and Splints. For vertical and horizontal wires, the house owner can choose between plastering the whole wall or covering wires with 2” (50mm) wide strips of cement plaster or stabilized mud plaster or leaving them open.

Source:

Households Details in Nepal (Data source: nra.gov.np)

The sequence of Installation of Retrofitting Measures on Walls (Manual prepared by: Rupal Desai, Rajendra Desai, CEDAP team with support from ODRC Team and UNDP Nepal)

How to do retrofitting of Load-bearing walls? 

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